February 28 - 29, 2008 Advisory Committee Meeting
Minutes

Youth Summary

Endurance training increases cardio-respiratory fitness among
children and adolescents, males and females; however no conclusions can be made
on race, ethnicity or SES. The data suggests endurance training increases VO2
max by 5 to 15%; however, the optimal dose of activity needed to obtain
improvements cannot be specified. A recent review concluded that an intensity of
greater than 80% of maximal heart rate with a frequency of 3 – 4 days per week
for 30 – 60 minutes of duration over 1 – 3 months improves cardio-respiratory
fitness. The data to support these conclusions consists of Type 1, 2, 3a and 3b,
strong evidence.

Physical activity is positively related to muscular strength.
Resistance training 2 or 3 times per week significantly improves muscular
strength. Resistance training increases muscular strength in children and
adolescents, males and females; however, the data cannot conclude anything on
the effects by race, ethnicity or SES. The type of evidence to support the
conclusions includes Type 2b, strong evidence.

Non-obese youth who have relatively high levels of physical
activity tend to have less adiposity; however, programs that increase physical
activity in normal weight youth typically have little effect on adiposity.
Controlled training studies with overweight youth have observed reductions in
overall adiposity and visceral adiposity with exposure to regular
moderate-to-vigorous activity 3 – 5 times per week with duration of 30 – 60
minutes each. There is no consistent evidence for a dose-response pattern and no
conclusions can be made on race, ethnicity or SES. These conclusions are
supported by Type 2a, 2b, 3a, 3b, strong evidence.

Physical activity is positively related to cardiovascular and
metabolic health in youth. There appears to be a dose-response relationship;
however, the pattern has not been determined. Very little is known about the
effects of age, maturity, gender, race, ethnicity and SES on the relationship
between physical activity and cardiovascular and metabolic health. This is
supported by Type 2a, 2b, 3a and 3b, strong, evidence.

Physical activity is positively related to bone health. Targeted
weight loading activities that simultaneously influence muscular strength, done
on a daily basis, are most effective. It is challenging to compare mode and dose
due to variability across studies. No conclusions can be made on a dose-response
relationship as more studies are needed. The relationship between physical
activity and bone health is influenced by age and development status and the
bone health of both boys and girls is improved by physical activity. No
conclusions can be made regarding race, ethnicity and SES. The conclusions are
supported by Type 1 and 3a, strong, evidence.

During childhood and adolescence, physical activity exerts a
beneficial effect on symptoms of anxiety and depression. The varying
methodologies and insufficient numbers of intervention trials preclude
inferences about dose-response patterns. The research cannot support any
conclusions regarding race, ethnicity or SES. Conclusions in the area of
depression are supported by Type 1, 2b, 3a and 3b, moderate strength, evidence.
Conclusions in the area of anxiety are supported by Type 1 and 3b, weak level of
strength evidence.

Overall, important health benefits can be expected to accrue to
most children and youth who participate daily in 60 or more minutes of
moderate-to-vigorous physical activity. Regular participation in resistance
exercise yields enhancement of muscular strength in the large muscle groups of
the trunk and limbs. Vigorous aerobic exercise results in enhanced
cardio-respiratory fitness and improved cardiovascular and metabolic health risk
factors. Weight loading activities promotes bone health.